Download or read book Molecular Dynamics of Supercritical Fluids written by Peihao Sun and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Supercritical fluids have received renewed interest in the past few decades because of their industrial applications. Underlying many of these applications is the high tunability of the fluid properties in the near-critical region, which is not captured by the widely held notion of the supercritical state as a single broad continuum. In fact, recent works show that the supercritical region can be divided into liquid-like and gas-like states based on thermodynamic and transport properties with a rapid crossover at the Widom line. However, the picture is less clear when it comes to the microscopic dynamics due to a lack of experimental data and physical understanding of the molecular-scale dynamics in the supercritical state. This dissertation focuses on this problem and contains two main parts. In the first part, a combination of inelastic X-ray scattering measurements and molecular dynamics (MD) simulations is used to study supercritical water. The results show that, contrary to commonly used models, there exist two components in the intermolecular dynamics, and it is the ratio between them that changes rapidly at the Widom line and drives the liquid-like to gas-like transition. In the second part, three additional systems--silicon, tellurium, and the Lennard-Jones fluid--are investigated via MD simulations, and the two-component behavior is found to be universal among these systems. The fraction of the liquid-like component is quantified and found to correlate with the degree of intermolecular bonding. The consequences of the two-component phenomenon for modeling supercritical fluid properties will be discussed.
Download or read book Molecular Dynamics Simulation of Supercritical Fluids written by Richard D. Branam and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Supercritical Fluids written by E. Kiran and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 602 pages. Available in PDF, EPUB and Kindle. Book excerpt: Supercritical fluids are neither gas nor liquid, but can be compressed gradually from low to high density and they are therefore interesting and important as tunable solvents and reaction media in the chemical process industry. By adjusting the density the properties of these fluids can be customised and manipulated for a given process - physical or chemical transformation. Separation and processing using supercritical solvents such as CO2 are currently on-line commercially in the food, essential oils and polymer industries. Many agencies and industries are considering the use of supercritical water for waste remediation. Supercritical fluid chromatography represents another, major analytical application. Significant advances have recently been made in materials processing, ranging from particle formation to the creation of porous materials. The chapters in this book provide tutorial accounts of topical areas centred around: (1) phase equilibria, thermodynamics and equations of state; (2) critical behaviour, crossover effects; (3) transport and interfacial properties; (4) molecular modelling, computer simulation; (5) reactions, spectroscopy; (6) phase separation kinetics; (7) extractions; (8) applications to polymers, pharmaceuticals, natural materials and chromatography; (9) process scale-up.
Download or read book Mechanistic Studies on written by Mayra B. Reyes and published by . This book was released on 1999 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Introduction to Supercritical Fluids written by Richard Smith and published by Newnes. This book was released on 2013-12-08 with total page 764 pages. Available in PDF, EPUB and Kindle. Book excerpt: This text provides an introduction to supercritical fluids with easy-to-use Excel spreadsheets suitable for both specialized-discipline (chemistry or chemical engineering student) and mixed-discipline (engineering/economic student) classes. Each chapter contains worked examples, tip boxes and end-of-the-chapter problems and projects. Part I covers web-based chemical information resources, applications and simplified theory presented in a way that allows students of all disciplines to delve into the properties of supercritical fluids and to design energy, extraction and materials formation systems for real-world processes that use supercritical water or supercritical carbon dioxide. Part II takes a practical approach and addresses the thermodynamic framework, equations of state, fluid phase equilibria, heat and mass transfer, chemical equilibria and reaction kinetics of supercritical fluids. Spreadsheets are arranged as Visual Basic for Applications (VBA) functions and macros that are completely (source code) accessible for students who have interest in developing their own programs. Programming is not required to solve problems or to complete projects in the text. Property worksheets/spreadsheets that are easy to use in learning environments Worked examples with Excel VBA Worksheet functions allow users to design their own processes Fluid phase equilibria and chemical equilibria worksheets allow users to change conditions, study new solutes, co-solvents, chemical systems or reactions
Download or read book Molecular Dynamics Simulations of Thermodynamic and Dynamical Properties of Liquids and Supercritical Fluids written by Ling Wang and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Supercritical Fluids written by Y. Arai and published by Springer Science & Business Media. This book was released on 2013-03-07 with total page 463 pages. Available in PDF, EPUB and Kindle. Book excerpt: The potential of supercritical fluid methods is presented in a comprehensive way. On the basis of a careful discussion of physical and chemical principles, the application of this method in process technology is demonstrated.
Download or read book Topics in Molecular Dynamics written by Ali Siavosh-Haghighi and published by . This book was released on 2004 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt: Rotational correlation functions are used to study the inhomogeneities in the structure of supercritical fluids by a computational molecular dynamics method. The effect of long-range interactions (such as electrostatic forces) versus short-range interactions (forces that decay faster than r -3) has been investigated by choosing relatively similar solute molecules with different dipole moments in particular benzene, toluene, aniline, phenol, and p -xylene with carbon dioxide as the solvent molecule in all cases. The result of this study showed the deterministic role of short-range interactions in rotational dynamics of mentioned solute molecules. More investigations along this line also have been performed by omitting the electrostatic interactions between solute and solvent molecules and by comparing the results with those derived from the "full" potential model case. The results of this part of study pointed to the importance of the charge density on atomic sites of solute molecule compare to the net strength of dipole moment of the solute molecule. Rotational dynamics of the mentioned solute molecules in the presence of methanol, as a dipolar co-solvent molecule, also has been investigated in order to elucidate the importance of the local dipole-dipole interactions between the solute and solvent molecules in a supercritical system. In a separate study, energy transfer at the surface of a Lennard-Jones system has been investigated as the initial stage of a study of more complex systems of energetic materials. We witnessed a more dramatic change in the rotational behavior for more polar solute molecules studied such as aniline and phenol at the presence of the co-solvent.
Download or read book Supercritical Fluids written by E. Kiran and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 775 pages. Available in PDF, EPUB and Kindle. Book excerpt: Supercritical fluids which are neither gas nor liquid, but can be compressed gradually from low to high density, are gaining increasing importance as tunable solvents and reaction media in the chemical process industry. By adjusting the pressure, or more strictly the density, the properties of these fluids are customized and manipulated for the particular process at hand, be it a physical transformation, such as separation or solvation, or a chemical transformation, such as a reaction or reactive extraction. Supercritical fluids, however, differ from both gases and liquids in many respects. In order to properly understand and describe their properties, it is necessary to know the implications of their nearness to criticality, to be aware of the complex types of phase separation (including solid phases) that occur when the components of the fluid mixture are very different from each other, and to develop theories that can cope with the large differences in molecular size and shape of the supercritical solvent and the solutes that are present.
Download or read book Molecular Dynamics Simulation of Dissolution of Cellulose in Supercritical Fluids and Mixtures of Cosolvents supercritical Fluids written by Ivan Vyalov and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Cellulose is insoluble in neat supercritical CO2 and the main objective of this work was to investigate mixtures of scCO2 with polar cosolvents for the development of new processing technologies for the cellulose dissolution. The objective is achieved by studying the dissolution process of monomer of cellulose and its various polymorphs. The effect of the t/d parameters on the dissolution process was analyzed by molecular dynamics simulation. We begin with analyzing structure of pure supercritical fluids and mixtures of supercritical fluids/cosolvents using unconvential tools: Voronoi tesselations and nearest neighbours approach.Thermodynamics of the mixtures of scCO2/cosolvents is analysed in order to check the validity of the potential models used in our simulations for what the method of thermodynamic integration to calculate the energy, entropy and free energy of mixing was applied. To analyze the dissolution of cellulose we started from studying the solvation free energy of cellobiose(cellulose monomer) which was calculated from molecular dynamics simulations using free energy perturbation method. The influence of conformational degrees of freedom on solvation free energy of cellobiose was also considered.Finally, the direct dissolution of cellulose crystals models in well-known good cellulose solvent(1-ethyl-3-methylimidazolium chloride) and then considered supercritical solvents. It was found that various mixtures of CO2 with cosolvents do not dissolve cellulose but they can considerably affect its crystalline structure whereas ammonia fluid can dissolve cellulose and this process is significantly influenced by temperature, pressure and density.
Download or read book Isomorphic Classical Molecular Dynamics Model for an Excess Electronin a Supercritical Fluid written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Supercritical and Other High pressure Solvent Systems written by Andrew J Hunt and published by Royal Society of Chemistry. This book was released on 2018-08-24 with total page 700 pages. Available in PDF, EPUB and Kindle. Book excerpt: Exploring the range and utility of high-pressure solvent systems across a variety of different chemical applications, this book brings together recent advances in supercritical technology and other pressurised-solvent systems. It provides an in-depth overview of the latest advances and developments and discusses the limitations and drawbacks that need to be addressed. Wherever possible, the greenness and economic viability of the different solvent systems is highlighted. This book is ideal for researchers and industrialists working in environmental science, green chemistry and biorefineries.
Download or read book The Liquid and Supercritical Fluid States of Matter written by John E. Proctor and published by CRC Press. This book was released on 2020-09-15 with total page 287 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book addresses graduate students and researchers wishing to better understand the liquid and supercritical fluid states of matter, presenting a single cohesive treatment of the liquid and supercritical fluid states using the gas-like and solid-like approaches. Bringing this information together into one comprehensive text, this book outlines how our understanding of the liquid and supercritical fluid states is applied and explores the use of supercritical fluids in daily life and in research, for example in power generation, and their existence in planetary interiors. Presents a single coherent treatment of the key knowledge about the liquid and supercritical fluid states Provides comprehensive survey of key fluid properties from the latest experiments and applies our theoretical knowledge to understand the behaviour of these real fluids Explores the consequences of recent advances in the field on our understanding in industry, nature, and in interdisciplinary research, including planetary science
Download or read book The Art of Molecular Dynamics Simulation written by D. C. Rapaport and published by Cambridge University Press. This book was released on 2004-04 with total page 568 pages. Available in PDF, EPUB and Kindle. Book excerpt: First time paperback of successful physics monograph. Copyright © Libri GmbH. All rights reserved.
Download or read book Molecular Dynamics Simulation of Supercritical Spray Phenomena written by and published by . This book was released on 2008 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: Results showed that the way the fluid-wall interaction is modeled in molecular dynamics simulations has a strong effect on the resultant simulation of liquid injection into a gas. It was found that modeling the wall as individual atoms (atomistic model) interacting with the fluid resulted in the fluid remaining in an injection tube absent any pressure or body force to force it into a gaseous region while a stochastically modeled diffusely reflecting wall with no attraction between the fluid and the wall resulted in the fluid being injected into the gas even in the absence of pressure or body forces. Since a non-atomistically modeled wall has reduced computational requirements compared to an atomistic wall, efforts centered on an examination of possible non-atomistic continuous fluid-wall interaction models that would not only correctly reproduce fluid thermodynamic properties such as pressure but would also reproduce the same fluid injection behavior as an atomistic wall model. Several non-atomistic fluid-wall models were examined in terms of their ability to correctly predict the fluid pressure in the injection tube over a range of fluid densities as well as their ability to reproduce atomistic wall injection behavior, but none were found able to reproduce atomistic wall behavior.
Download or read book Molecular Dynamics Studies of Transport Properties of Super critical Fluids written by Obika C. Nwobi and published by . This book was released on 1997 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Supercritical Water Chemistry Molecular Dynamics Simulations and Flow Reactor Studies written by Dimitrios Theofanis Kallikragas and published by . This book was released on 2019 with total page 438 pages. Available in PDF, EPUB and Kindle. Book excerpt: Supercriticalwater (SCW) exhibits unique properties that differentiates it from its low temperature behaviour. Hydrogen bonding is dramatically reduced, there is no phase boundary between liquid and gaseous states, heat capacity increases, and there is a drastic reduction of the dielectric constant. Efforts are underway for researchers to harness these properties in the applications of power generation and hazardous waste destruction. However,the extreme environment created by the high temperatures,pressures and oxidizing capabilities pose unique challenges in terms of corrosion not present in subcritical water systems. Molecular Dynamics (MD) simulations have been used to obtain mass transport, hydrationnumbersand the influence on water structure of molecular oxygen, chloride, ammonia and iron (II) cations in corrosion crevicesin an iron (II) hydroxide passivation layer. Solvation regimes marking the transitions of solvation based versus charge meditated processes were explored by locating the percolation thresholds of bothphysically and hydrogen bonded water clusters. A SCW flow through reactor was used to study hydrogen evolution ratesover metal oxide surfaces, metal release rates and the kinetics for the oxidation of hydrogen gas by oxygen in SCW. Insights into corrosion phenomenaare provided from the MD results as well as the experimental determination of flow reactor water and hydrogen chemistry.
